The objectives of the research are to obtain a detailed understanding of development and differentiation in eucaryotic organisms. At the biochemical level, this involves an understanding of mechanisms and controls governing translation of genetic information. The current studies are concerned with the process whereby ribosomes attach to a specific messenger and aminoacyl tRNA programmed by the messenger becomes linked to form a peptide. Such studies should lead to the analysis of more complex situations, particularly those where several messengers are available for translation and yet only a limited number prove to be functional.